The present invention relates to an apparatus for applying a protective substance to a welding seam of a metallic sleeve, including a frame, a container disposed within the frame holding a protective substance, and a drivable applicator roller disposed in the container at least in part contact with the protective substance and applying it to the seam of the metallic sleeve.
In Swiss Pat. No. 624,591 there is described an apparatus for applying a protective layer to the seam of a can component, for example a sleeve. Lacquer is applied to the seam from the periphery of a driven disc-shaped roller partially dipping into a container containing the lacquer, and wherein lacquer is also applied to regions disposed on each side of the seam. In order for the bulge-like seam to be reliably covered, more lacquer is fed from the periphery of the roller to the seam than can be received by the seam. Within a contact region of the periphery of the roller with the sleeve, any excess lacquer is pressed outwardly from the seam and forms on each side of the coated seam a bulging coating.
In a drying process which follows, bubbles may form in the bulging coating and may result in an impaired coating due to an imperfect drying process.
Furhermore, the visual impression of the seam covered with the coating is poor and consumption of the lacquer increased.